It is known that compositions comprising the tunica submucosa of the intestine of warm-blooded vertebrates can be used as tissue graft materials. See U.S. Pat. Nos. 4,902,508 and 5,281,422. The tissue graft compositions described in those patents are characterized by excellent mechanical properties, including a high burst pressure, and an effective porosity index which allows such compositions to be used beneficially for vascular graft and connective tissue graft constructs. When used in such applications the graft constructs appear not only to serve as a matrix for the regrowth of the tissues replaced by the graft constructs, but also promote or induce such regrowth of endogenous tissue. Common events to this remodeling process include: widespread and very rapid neovascularization, proliferation of granulation mesenchymal cells, biodegradation/resorption of implanted intestinal submucosal tissue material, and absence of immune rejection.
It is also known that intestinal submucosa can be fluidized by comminuting and/or enzymatic digestion, without loss of its apparent biotropic properties, for use in less invasive methods of administration (e.g., by injection or topical application) to host tissues in need of repair. See U.S. Pat. No. 5,275,826.
Surprisingly, it has been found that submucosal tissue is also capable of promoting endogenous regrowth and healing of damaged or diseased cardiac tissues, including the endocardium, pericardium, and myocardium. Myocardial tissue comprises the middle muscular tissue of the heart wall. Cardiac muscle tissue differs from smooth and skeletal muscle in that the nuclei are centrally located, the cells form a syncytium, and the cells exhibit the property of spontaneous contractibility or "automaticity."
In accordance with the present invention submucosal tissue of a warm blooded vertebrate is used for the preparation of a graft construct that promotes endogenous regrowth and healing of damaged or diseased cardiac tissues upon contact of said damaged or diseased tissues with the composition.
The present submucosal tissue graft compositions can be implanted or injected into a vertebrate host to induce the repair or replacement of damaged or defective heart tissues. In one embodiment damaged or diseased myocardial tissues are contacted in vivo with a composition comprising intestinal tunica submucosa of a warm blooded vertebrate to enhance the formation of endogenous tissues having spontaneous contractile properties.